Alcatel SPEED TOUCH 710, User Manual

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NA(P)T and AST710
transparency
In this subsection
Consequences of
NA(P)T on layers
10 Configuration and Use - PPP & IP Routing
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3EC 17605 AAAA TCZZA Ed. 02
10.4.6 NA(P)T and AST710 Transparency
As described in subsection 10.4.5, the AST710 can perform
NA(P)T to decouple your local IP addresses from the public IP
address negotiated during a PPP session.
However, this feature comes at the expense of the
AST710
transparency. This because a number of protocols that are layered
on top of either TCP/IP, or UDP/IP do not adhere to the ISO/OSI
reference model.
Note : The ISO Open Systems Interconnection (OSI) reference model promotes
the layered implementation of communications protocol stacks. Layers from
protocol stacks implemented according to this model can be changed without
affecting the upper or lower layers.
Consequences of NA(P)T on Layers
AST710 Solutions
Via the PPPoAtoPPTP Relay
PPPtoDHCP Spoofing.
An important consequence is that changing IP addresses or
TCP/UDP ports via NA(P)T affects the other layers as well.
Due to these changes, applications that are the ultimate
consumers of the protocols cannot decode the information
correctly anymore.